I know that you can use free actions after a charge, including using an action point to extend your turn, but what exactly does this entail? In addition to gaining your extra action do you re-gain access to other actions you hadn't yet used?

Simple example: Rogue charges, uses an action point, then makes a second standard attack. Can he also use a minor action at that point for low slash, or a move action that he hadn't yet used to shift away?

No, when you spend an action point to take an extra action after a charge, you only get that one extra action. You don't regain access to your unused actions.

After charging, you can't take any further actions except free actions, that's the general rule. Spending an action point as a free action gives you one extra action which you can take, that's the specific that trumps the general. There's nothing about an action point that says you get any other actions than the one action you gain.

OD&D, 1E and 2E challenged the player. 3E challenged the character, not the player. Now 4E takes it a step further by challenging a GROUP OF PLAYERS to work together as a TEAM. That's why I love 4E.

"Your ability to summon a horde of celestial superbeings at will is making my ... BMX skills look a bit redundant."

"People treat their lack of imagination as if it's the measure of what's silly. Which is silly." - Noon

"Challenge" is overrated. "Immersion" is usually just a more pretentious way of saying "having fun playing D&D."

"Falling down is how you grow. Staying down is how you die. It's not what happens to you, it's what you do after it happens.”

Need a few pre-generated characters for a one-shot you are running? Want to get a baseline for what an effective build for a class you aren't familiar with? Check out the Pregen thread here
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Also, I've recently done an episode on "Refluffing". You can check that out here

As a note there are ways to get around this problem (Warforged Juggernaut). You don't regain your actions, but you don't lose them from charge either.

The Invincible Vanguard epic destiny allows you to take any action you want after a charge, starting at 21st level, without using an action point.

There are also half a dozen other ways to go about it, I was just listing one . Also, the ED requires you to charge and take a basic attack in order to get the other benefits. Which can be pretty annoying for some classes (Like barbarians for instance).

Need a few pre-generated characters for a one-shot you are running? Want to get a baseline for what an effective build for a class you aren't familiar with? Check out the Pregen thread here
If ever you are interested what it sounds like to be at my table check out my blog and podcast here
Also, I've recently done an episode on "Refluffing". You can check that out here

As a note there are ways to get around this problem (Warforged Juggernaut). You don't regain your actions, but you don't lose them from charge either.

The Invincible Vanguard epic destiny allows you to take any action you want after a charge, starting at 21st level, without using an action point.

There are also half a dozen other ways to go about it, I was just listing one . Also, the ED requires you to charge and take a basic attack in order to get the other benefits. Which can be pretty annoying for some classes (Like barbarians for instance).

The basic attack is only required to get the Invigorating benefit. None of the ED's other charge related benefits require you to make a basic attack.